Vehicle speed or cruise control systems typically incorporate an actuator for positioning the throttle of the vehicle engine in relation to the error, or difference, between an operator determined speed command Ncmd and a measure of the actual vehicle speed Nv. In other words, the speed error is periodically computed and used to determine a position command for the throttle or throttle actuator. The gain of the control is defined as the scheduled change in position command per unit change in speed error.
Ordinarily, the control gain is set relatively high in order to achieve accurate steady state speed control of the vehicle. Control under such conditions is referred to herein as the "normal" mode of operation. However, in modes of operation which accelerate the vehicle to a new speed, the relatively high gain of the normal mode of operation results in excessive throttle movement which adversely affects the driveability of the vehicle. Such modes include the "resume" mode in which the speed control is reactivated to a previously set speed command following an operator-interruption of the control, and the "acceleration" mode in which the operator requests the control to increase the speed command.